Adjusting Headlights: See Well and be seen Well

When oncoming vehicles blink at you in the dark, you know: Something is wrong with your headlights. The same applies if you can see almost nothing in the dark. Then your headlights are either defective or incorrectly adjusted. This should be corrected quickly.

A wrong adjustment of low beam and high beam causes a wrong inclination angle of the headlight. This means that the light cannot adequately illuminate the road in front of the car. Only correctly adjusted headlights ensure good visibility in the dark and thus the necessary safety.

We tell you how to adjust most headlights. However, you should only do this if you have a lot of experience. In general, we advise you to go to a specialist workshop for this work. With special headlight adjustment devices, the headlight adjustment is made there quickly and cheaply.

Instructions: Adjusting the headlights yourself

Depending on the vehicle make, model and headlight type, you can adjust the headlight beam for low beam and high beam yourself. With conventional halogen headlights such as H4 or H7, you can usually do this with a little practice. With other types of headlights, you can only adjust the basic setting – the fine-tuning for the light is done by the electronics.

Since 1990, every new car must have a headlamp leveller. With this, you can change the headlight range of the low beam in different load conditions, such as before a vacation trip. At least if the regulation is done manually. The adjustment wheel is usually located to the left of the steering wheel.

The headlight range is adjusted by changing the angle of inclination of the headlights. In most vehicles, the angle of inclination of the low beam is between 1 and 1.2 degrees, that of the high beam between 2 and 2.5 degrees. In most cases, a sticker on the headlight housing provides information about the prescribed number of degrees.

The headlights must be adjusted:

The spotlights contain the illuminants and emit the light to the front. Since it always propagates in a straight line in space, the position and direction of the lamps are crucial. After all, when driving in the dark, you want to see a lot of road without dazzling oncoming traffic. The projected light cone must therefore cover as large an area as possible in front of the car, but leave out oncoming traffic. This is currently achieved by asynchronous illumination, with the light cone always extending further to the right than to the left. Only by adjusting the headlights can it be ensured that the driver has optimum vision and that other road users are not endangered. The headlights must be adjusted:

  • when driving with a fully loaded trunk
  • when driving with a trailer
  • when headlights set too high dazzle drivers in oncoming traffic
  • if the headlamps are set too low, minimizing visibility when driving
  • after new headlights have been installed
  • if you do not see enough in the dark
  • after a rear-end collision or a front-end repair

Adjusting headlights without an adjuster

If the car has a conventional lighting system, you can adjust it yourself. For this you need

  1. a white or bright wall
  2. a meter ruler
  3. adhesive tape

Step 1: The preparation

Fill the tank at least halfway
Set tire pressure to the correct value
Load driver’s seat with at least 75 kilograms of weight
Search for setting data/inclination angle of headlights

Step 2: The distance

Find a bright or white wall
Park car 10 meters from bright wall (five meters if necessary)
Align car

Step 3: The marking

Mark horizontal auxiliary line with adhesive tape: The height of the line must correspond to the height of the headlight center. Mark vertical auxiliary lines: Mark distance between both headlights. Then draw two vertical lines, each marking the center of the two headlights.

Step 4: The correction line

Mark a second horizontal line with the tape. At a tilt angle of 1.2 degrees and a distance of ten meters between the car and the wall, this line is drawn twelve centimeters below the first line. At five meters, it is half.

Step 5: Adjust the headlights

Switch on the headlights: If the center of the light cone hits the correction line, the tilt angle is correct. If not, you need to turn the screw above the headlight until the vertical adjustment is correct. When turning clockwise, the tilt angle is raised. Ideally, the most intense part of the light is to the left or right of the two vertical lines. The light cone can be adjusted with the screws on the left and right of the headlight.

Many xenon or LED headlights, on the other hand, as well as headlights with automatic adjustment, you cannot adjust precisely yourself because they have automatic headlight range control. However, they can usually be adjusted to the basic position. In the case of complex high-tech lighting systems that steer or mask individual areas of the light cone (matrix LED), you can no longer adjust anything yourself. If one of these headlight types is out of alignment, you should go to a specialist workshop or an automotive service center.

Have headlights adjusted at a workshop

It is easier and faster to have the headlights adjusted at a workshop. As a rule, checking the correct setting is part of the inspection scope. Some workshops also offer fall checks, during which the headlights are checked. During the annual light test in October, drivers can have their car’s headlights checked free of charge at very many automotive workshops.

In the past, the 10-meter wall method was used to adjust headlights. Although this is still a legally prescribed test method today, devices that require significantly less space and are designed for the complicated, more modern headlight systems are now mostly used.

Professional adjustment of headlights is currently performed almost exclusively with the special headlight adjustment devices, or SEG for short. These devices simulate the 10-meter wall method, except that the distance is reduced to 50 cm by a lens. This allows headlight adjustment to be performed in a smaller space. Since even a misadjustment of a few millimeters can have significant effects at a greater distance, there are many requirements that the measurement environment must meet. Professional equipment and knowledge are needed to adjust the headlights precisely and optimally, which is why correction in a workshop is ideal.

How long does the light test take?

Depending on the make, model and type of headlight, a specialist only needs a few minutes to check the headlights with the special headlight adjusting device (SEG). If one or both headlights need to be adjusted, it can take longer. If individual sensors are defective and the headlights need to be repaired, you will have to wait longer.

What does the light test cost?

The cost of adjusting headlights is low. Drivers pay nothing for the light test at most garages in October. During an inspection, the check is usually included, depending on the vehicle. If you have to have the headlights adjusted outside of the campaigns and the inspection, you pay between 10 and 40 euros, depending on the workshop. The decisive factor is the amount of work involved in the adjustment.

How expensive is it to have headlights adjusted at the workshop?

Adjusting headlights is a matter of minutes for the workshop and usually costs no more than $10-20. It is somewhat more expensive for headlights with automatic headlight range control, such as xenon burners, because the corresponding control unit has to be relearned. To do this, the headlights must first be set to their basic position. However, the adjustment should not cost more than $40, even for xenon headlights. By the way, workshops often advertise a free light test to attract customers. There’s nothing wrong with that, but if it’s a matter of replacing parts, then compare workshop prices and buy the spare parts from us to save money.

What do you have to consider when adjusting the headlights?

Even when adjusting headlights, the devil is in the details. Therefore, observe the following instructions:

  1. The surface must be level.
  2. The air pressure of the tires must comply with the manufacturer’s specifications.
  3. Adjustment is done with a driver in the car. If you are working alone, weigh down the seat.
  4. Remove heavy payloads if they do not usually drive them around.
  5. Headlight leveling adjustment must be turned to zero.
  6. In the case of automatic headlamp leveling, the control unit must be taught and the headlamps must be set to the initial position.

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